"Another thing to consider for soundstage definition improvement is what sits under your components."
Agreed - I have had great success using 3 brass cones under all of my components. I also tried wood cones, which provided audible improvements, but the brass cones provided a little more detail and clarity.
In my case, the components sit on a granite tile with a thin rubberized mat between it and the MDF shelf.
The brass cones vary in diameter/depth, from a 2.5" dia cone 1.25" high for the turntable down to 3/4" dia cone 1/4" high for my Bluesound Node streamer.
Unfortunately, all of the cones were custom made so I cannot recommend a brand, but there are some good commercially available products out there.
Regards - Steve